Development and automation of microelectromechanical systems-based biochip platform for protein assay

Miniaturized devices (lab-on-a-chip) for performing laboratory operations on microscale are appealing. Low sample requirement is one of the major advantages of these devices, therefore less costs is needed for running such platforms and also fewer wastes to be handled. Together with the unique behavior of liquids on microscale facilitating control of molecular diffusion and interaction makes miniaturized devices particularly useful in chemical synthesis as well as biological and/or chemical analysis. In this report, we designed a microfluidic platform with programmable microvalves capable to carry out routine operations. This platform was further optimized to contain universal sample-processing capabilities, using a three-layered hybrid PDMS–PDMS–glass structure. Precise programmable control of the volumetric flow rate can be achieved via the discrete digital control of fluids in pneumatically actuated microvalves. The specific protocols of the system are optical path platforms consisting of MEMS combined with SU-8 arrays in microfluidic reactors for parallel biological analysis. To demonstrate the programming capabilities for biomolecular assay integration, we developed an automated assay with streptavidin immobilized on the SU-8 patterned surface; these optical microfluidic platforms featured with a low sample requirement (0.5 μl per single assay) were then employed as a protein sensor, which has working concentrations ranged from 39.3 to 2500 nM for detecting biotin in the sample solution. The results suggest potential applications of these platforms in either routine assay purposes or specific applications such as high-throughput screening of protein–protein and protein–ligand interactions.